LCWS 31/5/2007 Erik Johnson STFC,RAL 1

ILC Vertex Detector Mechanical Studies

Erik JohnsonOn behalf of the LCFI collaboration

STFC, Rutherford Appleton Laboratory

LCWS 31/5/2007 Erik Johnson STFC,RAL 2

Outline

• Approaches to building a vertex detector

• Resource available• Future plans

LCWS 31/5/2007 Erik Johnson STFC,RAL 3

Approach for Building a Vertex Detector

• Close to interaction point

• Long lever arm• Low mass

– cooling

• Robust• Uniformity within a

layer

LCWS 31/5/2007 Erik Johnson STFC,RAL 4

LCFI Baseline Design• Individual long ladders• Arranged in a barrel

– Active length 250mm

LCWS 31/5/2007 Erik Johnson STFC,RAL 5

Barrel Layout

Beam pipe Ladder (detector element)

Foam cryostat

Beryllium support shell

Spring

Ladder block

Annulus block

Fixed end Sliding end

Readout and drive chips

Substrate

Silicon sensor

Beryllium support shell

Annulus and ladder blocks

LCWS 31/5/2007 Erik Johnson STFC,RAL 6

Barrel Layout

Layer no

No of Ladders

Radius(mm)

Active length(mm)

Active width(mm)

Tilt angle

Overlap(mm)

1 8 15(19) 100 13 0 0

2 8 26(28.5) 250 22 0 0.42

3 12 37 250 22 15 1.3

4 15 48 250 22 15 0.86

5 19 60 250 22 15 1.2

• Looking at:– the radius of the layers– width of elements– tilt angle

LCWS 31/5/2007 Erik Johnson STFC,RAL 7

Ladder Developments

• Foams – + low mass– take up space

• Prototypes of ladders– SiC (silicon carbide foam)– RVC (reticulated vitreous carbon foam)

• Some success with both• Problems with procuring thin silicon• Have new supplier of thin silicon –

Aptek Industries Inc

LCWS 31/5/2007 Erik Johnson STFC,RAL 8

SiC Foam Ladder• 20 um thick silicon• 1.5 mm thick SiC foam

– 8% relative density• Silicone adhesive pads

– 1mm diameter 200 microns high on ~5mm pitch

• ~0.14% X0SiC ladder

ladder block

glue

annulus block

mm

um

mm

um

LCWS 31/5/2007 Erik Johnson STFC,RAL 9

RVC Foam/Silicon Sandwich Ladder

• 20 micron thick silicon• 1.5 mm thick RVC foam

– 3% relative density• Silicone adhesive pads

– on ~5mm pitch• Tension ~1.5 N• ~0.08% X0

RVC sandwiched ladder

silicon spacer

ladder block

glue

annulus block

Tension

mm

um

mm

um

LCWS 31/5/2007 Erik Johnson STFC,RAL 10

Possible Alternatives

• Carbon fibre substrates

• Double sided detectors – reduce number of layers

• Use a Carbon fibre shell for one or more layers

LCWS 31/5/2007 Erik Johnson STFC,RAL 11

Resources Available

• Lab tools:– Cold survey cryostat with high precision laser

micrometer– Glue robot– Cooling test stand

LCWS 31/5/2007 Erik Johnson STFC,RAL 12

Future Plans

• Continue prototyping foam ladders• Build and test carbon fibre shell• Computer simulations

– FEA and CFD